1. Field of the Invention
The present invention relates to mechanical tree pruning devices including chain saws and hedge trimmers, which have the capability of operating at unusual heights, 20 feet or more from the ground, and the cutting of unusally large tree limbs, up to 51/2 inches in diameter, or more.
The novel design of the invention permits a plurality of several embodiments which are differently powered and can be built from the same principal components in different price ranges and for different market segments.
2. Description of the Prior Art
Numerous chain saw type devices exist in the prior art for the purpose of pruning tree limbs and trimming hedges, but they have serious disadvantages.
One such disadvantage is the lack of means for angular cutting head adjustment of the chain saw relative to the holding means, usually a pole of some sort. The capability of cutting head adjustment provides a better cutting angle and facilitates the location of the chain saw on top of the limb to be cut, thereby avoiding pinching of the saw during the cutting operation, which is usually at the side or bottom of the limb with prior art devices.
No means for angular cutting head adjustment is disclosed in U.S. Pat. Nos. 3,158,933 (Davis); 3,657,813 (Knight); 3,731,382 (Wroe); 4,048,722 (Howard); 4,122,601 (Katsuya); 4,179,805 (Yamada); 4,341,017 (Janczak); and 4,483,070 (Junkerman).
Another disadvantage of chain saw devices with pole members for pruning tree limbs is the absence of lubrication means for the chain saw. Of the devices disclosed in U.S. Pat. Nos. 2,703,928 (Southwick); 2,756,784 (Cherem); 3,158,933 (Davis); 3,657,813 (Knight); 4,048,722 (Howard); 4,122,601 (Katsuya); 4,179,805 (Yamada); and 4,483,070 (Junkerman), none has any means for lubrication of the chain saw at all.
U.S. Pat. No. 3,731,382 (Wroe) is limited to lubrication from its engine and requires a special lubrication line therefor, but has no means for lubrication for a manually operated tree pruner such as applicant's invention, or self-contained lubrication means provided by applicant's invention.
U.S. Pat. No. 4,341,017 (Janczak) provides lubrication of a chain saw but is limited to complicated means requiring a hydraulic pump, and an oil line extending along the length of the Janczak guide bar, and has no disclosure of a self contained lubrication means in the cutting head, such as in the present invention. Janczak is further limited by the absence of any means for adjusting the longth of the guide bar.
U.S. Pat. No. 4,207,675 (Causey) discloses no means for lubrication of its cutting head element and is further limited to an electric motor as a power source.
Further, prior art devices using shaft driven transmission elements such as shaft bevel gear combinations and the like, are limited to a few feet in length because of the considerable torque required for operation of a chain saw, shaft windup, shaft whip, and excessive weight.